A computer program for simulating ground-water flow in three dimensions is presented. This report includes detailed explanations of physical and mathematical concepts on which the model is developed. Ground-water flow within the aquifer is simulated by using a block-centered finite-difference approach. The program is written in Fortran 77 and has a modular structure, which permits the addition of new packages to the program without modifying existing packages.

/pdf/a-modular-three-dimensional-finite-difference-ground-water-4wzl834v4y.pdf

A modular three-dimensional finite-difference ground-water flow model

Petroleum Reservoir Simulation

This article describes the governing equations, computational algorithms, and other components entering into the Community Multiscale Air Quality (CMAQ) modeling system. This system has been designed to approach air quality as a whole by including state-ofthe-science capabilities for modeling multiple air quality issues, including tropospheric ozone, fine particles, acid deposition, and visibility degradation. CMAQ was also designed to have multiscale capabilities so that separate models were not needed for urban and regional scale air quality modeling. By making CMAQ a modeling system that addresses multiple pollutants and different spatial scales, it has a “one-atmosphere” perspective that combines the efforts of the scientific community. To implement multiscale capabilities in CMAQ, several issues (such as scalable atmospheric dynamics and generalized coordinates), which depend on the desired model resolution, are addressed. A set of governing equations for compressible nonhydrostatic atmospheres is available to better resolve atmospheric dynamics at smaller scales. Because CMAQ is designed to handle scale-dependent meteorological formulations and a large amount of flexibility, its governing equations are expressed in a generalized coordinate system. This approach ensures consistency between CMAQ and the meteorological modeling system. The generalized coordinate system determines the necessary grid and coordinate transformations, and it can accommodate various vertical coordinates and map projections. The CMAQ modeling system simulates various chemical and physical processes that are thought to be important for understanding atmospheric trace gas transformations and distributions. The modeling system contains three types of modeling components (Models-3): a meteorological modeling system for the description of atmospheric states and motions, emission models for man-made and natural emissions that are injected into the atmosphere, and a chemistry-transport modeling system for simulation of the chemical transformation and fate. The chemical transport model includes the following process modules: horizontal advection, vertical advection, mass conservation adjustments for advection processes, horizontal diffusion, vertical diffusion, gas-phase chemical reactions and solvers, photolytic rate computation, aqueous-phase reactions and cloud mixing, aerosol dynamics, size distributions and chemistry, plume chemistry effects, and gas and aerosol deposition velocity estimation. This paper describes the Models-3 CMAQ system, its governing equations, important science algorithms, and a few application examples. This review article cites 114 references. DOI: 10.1115/1.2128636

Review of the Governing Equations, Computational Algorithms, and Other Components of the Models-3 Community Multiscale Air Quality (CMAQ) Modeling System

A special form of depolarization of polymer electrets is described: the thermally stimulated discharge (TSD). After reviewing its principles and exposing its mathematical analysis, results are presented which show that TSD is a powerful method to gain insight into the molecular mechanisms of the electret effect. In fact, TSD reveals all low-frequency molecular motions. It enables one to determine, e.g., the glass-rubber transition of polymers. Its merits are compared with those of isothermal dielectric, and mechanical methods of investigation.

/pdf/thermally-stimulated-discharge-of-polymer-electrets-4g5f8rvudd.pdf

Thermally Stimulated Discharge of Polymer Electrets

https://web.iitd.ac.in/~arunku/files/CVL722_Y15/Surface%20chemistry%20of%20ferrihydrite_Fuller.pdf

Von Rosenberg

Papers

Methods for the Numerical Solution of Partial Differential Equations